package ${basepackage}.util;

import javax.servlet.*;
import java.io.IOException;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;

/**
 *
 */

public class CharacterEncodingFilter implements Filter
{

    /**
     * The default character encoding to set for requests that pass through this
     * filter.
     */
    protected String encoding = null;

    /**
     * The filter configuration object we are associated with. If this value is
     * null, this filter instance is not currently configured.
     */
    protected FilterConfig filterConfig = null;

    /**
     * Take this filter out of service.
     */
    public void destroy()
    {

        this.encoding = null;
        this.filterConfig = null;

    }

    /**
     * Select and set (if specified) the character encoding to be used to
     * interpret request parameters for this request.
     *
     * @param request
     *            The servlet request we are processing
     * @param response
     *            The servlet response we are creating
     * @param chain
     *            The filter chain we are processing
     *
     * @exception java.io.IOException
     *                if an input/output error occurs
     * @exception javax.servlet.ServletException
     *                if a servlet error occurs
     */
    public void doFilter(ServletRequest request, ServletResponse response,
        FilterChain chain)
        throws IOException, ServletException
    {

        // Conditionally select and set the character encoding to be used
        if (request.getCharacterEncoding() == null)
        {
            String encoding = selectEncoding(request);
            if (encoding != null)
            {
                request.setCharacterEncoding(encoding);
            }
        }

        // Pass control on to the next filter
        chain.doFilter(request, response);
    }


    /**
     * Place this filter into service.
     *
     * @param filterConfig
     *            The filter configuration object
     */
    public void init(FilterConfig filterConfig)
        throws ServletException
    {

        this.filterConfig = filterConfig;
        this.encoding = filterConfig.getInitParameter("encoding");

    }

    /**
     * Select an appropriate character encoding to be used, based on the
     * characteristics of the current request and/or filter initialization
     * parameters. If no character encoding should be set, return
     * <code>null</code>.
     * <p>
     * The default implementation unconditionally returns the value configured
     * by the <strong>encoding</strong> initialization parameter for this
     * filter.
     *
     * @param request
     * The servlet request we are processing
     */
    protected String selectEncoding(ServletRequest request)
    {

        return (this.encoding);

    }

}
